In the past a doorbell switch, annunciator, and chime device included a case having a lower window for displaying a name card, an upper window for displaying messages, and a doorbell pushbutton switch located between them. A dial was provided around the pushbutton switch; the dial was manually set to identify the expected return time of an absent occupant. Lamps were positioned behind the upper slot for illuminating a photographic film positioned in the upper slot. The photographic film contained the messages the occupant desired to display. The lower slot was designed to receive a name card for display. A two way switch was connected between the pushbutton switch, lights, and chime. The switch could be thrown to a first position to connect the lights to a source of power to illuminate the message and to break the doorbell circuit, and to a second position to turn off the lights and connect the doorbell. Those persons skilled in the art desiring more information of this prior art device are referred U.S. Pat. No. 2,343,009 issued Feb. 29, 1944 to J. A. Hall.
Another prior art device included a musical door chime connected to a clock for annunciating the time. The device includes a read only memory (ROM) for storing a repertoire of musical tunes one of which is displayed when a doorbell pushbutton switch is pressed. The tune to be played is selected by a keyboard connected to a microprocessor. The microprocessor reads from memory each digitally encoded musical note for a note strike and decay circuit. This circuit converts the digital note to analog signals for energizing a loudspeaker. In addition, a clock generates the time for the microprocessor to automatically ring the chimes to indicate the hour of the day. Those persons skilled in the art desiring more information for this device are referred to U.S. Pat. No. 4,326,276 issued Apr. 20, 1982 to W. M. Scott, Jr.
Other prior art doorbell devices of interest includes a door signal regulator circuit which rings the bell at a constant rate regardless of whether the pushbutton is depressed only momentarily or for a long period of time (U.S. Pat. No. 2,909,771 issued Oct. 20, 1959). Another doorbell with hour-of-return indicator, includes a doorbell enabling switch and two dials (hours and minutes) concentrically mounted about the pushbutton switch for setting and lighting the time of return in a window when the doorbell is cut off and enabling the doorbell when non-lettered spaces of the dials are positioned in the window. Still another door signal device includes a key controlled lock switch to provide a visual indication when the occupant is absent and has locked his door. The doorbell is cut off when the door is locked (U.S. Pat. No. 2,039,975 issued May 5, 1936).
Major differences between the prior art devices and the present invention exist. The programmable doorbell control device of the present invention is a low power device connectable to existing household wiring. The device has automatic and manual modes of operation. The automatic mode provides a means of disabling and re-enabling the doorbell by programming the device to perform these functions at a specified time. When disabled the device will display a selected one of a plurality of messages and sound an audible tone when the button is pressed, in order to direct the visitor's attention to the displayed message. When desired the manual mode is selected to override the automatic operation mode. The device continuously displays the name of the party occupying the home.
Thus, a visitor pushing a button hears a tone directing his attention to the display for receiving a message. A repertoire of messages is provided, including a PLEASE KNOCK message to localize the sound when an occupant such as, for example, a baby is sleeping and not to be disturbed. Or, if the occupant is a day time sleeper, a DAYTIME SLEEPER message, or, if the occupant does not want to be disturbed, a DO NOT DISTURB message can be displayed. These differences constitute features which are all advantages over the prior art.